Britain’smostnotoriousserialkiller,DennisNilsen,confessedtokilling15peoplein1983.Overafive-yearperiod,hepickedupvulnerableyoungmen,luredthembacktohishomeandstrangledthem,beforedisposingoftheirbodiesunderthefloorboards. Thetruthabouthowandwhyhekilledhasbeenthesubjectofmuchspeculationinbooksanddocumentariesoverthedecadessince.Now,withuniqueaccesstoawealthofpersonalarchiveleftinhiscellafterhisdeath,includingover250hoursofnever-before-publishedcassettetapesofhisprivaterecordings,thisfilmwilltakeusintoNilsen’sworld.FromayoungboygrowingupinaquietScottishfishingvillagetoacold-bloodedmurdererprowlingthestreetsofLondon. Setagainstthebackdropof1980sBritain,whenmassunemploymentdrewyoungmentoLondoninsearchoftheirfortunes,onlytofindthemselvesdestituteandeasyprey,andweavingtogetherinterviewsfrompolice,journalists,survivors,bereavedfamilies,and-forthefirsttime-thekiller’sownvoice,thisfeaturelengthdocumentaryexploreshowNilsenwasabletogetawaywithmultiplemurdersandattacks,unchallenged,forfiveyears.